Sealing ring made of a high-performance thermoplastic material and liquid silicone

ABSTRACT

A sealing ring for a header of an implantable device has an outer ring and an inner ring. The outer ring is formed with, or of, a high-performance thermoplastic material. The inner ring is formed with, or of, liquid silicone or polyurethane. The inner and outer rings are arranged with a form-fit relative to each other. There is also described a method for manufacturing such a sealing ring and also a contact socket and an implantable device with such a sealing ring.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority, under 35 U.S.C. § 119, of Europeanpatent application EP 18194056, filed Sep. 12, 2018; the priorapplication is herewith incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a sealing ring, in particular for usein a connection head (header) of an implantable device, and to a methodfor manufacturing the sealing ring.

Insulating sealing elements in pluggable contact sockets in connectionheads or headers of implantable devices are known in the prior art. Theheader is used here in particular to conduct electrical pulses from thecore of the implantable device to an electrode lead that is plugged intothe header, and also possibly in the reverse direction. The parts of theheader, in particular the contact socket, are typically cast into ablock of epoxy resin so as to be protected against the influences of thetarget environment. The aforementioned sealing elements are intended toensure in particular electrical insulation between the electricallyconductive contacts in the header. Furthermore, such seal elements canbe used as an attachment surface for the above-mentioned epoxy resin andso as to produce a certain distance between the electrically conductivecontacts.

By way of example, published patent application US 2008/0177167 A1discloses insulating sealing elements in pluggable contact sockets,which consist of a core that is used to ensure the distance between twoelectrical contacts, as a stop for the assembly process, as anattachment surface for joining materials, and for mechanical fixing of aseal (“wiper seal”). The disclosed materials for this core arepolycrystalline materials, single crystals, and crystalline sapphire.

The general structure of pluggable contact sockets in medical implantsis disclosed for example in published patent application US 2015/0018909A1, in U.S. Pat. No. 8,751,002 B2 or in published patent application US2009/0017668 A1.

Furthermore, published patent application US 2011/0059639 A1 describesthe use of silicone for sealing and for electrical insulation in respectof contact sockets for medical implants. Published patent application US2009/0017668 A1 discloses the use of liquid silicone rubber (LSR) forinsulating sealing elements in pluggable contact sockets.

Nevertheless, there is still a need for suitable designs for suchsealing elements which fulfil the above-mentioned objectives to thebest-possible extent.

SUMMARY OF THE INVENTION

Against this background it is an object of the invention to provide asealing ring and a manufacturing method which overcome theabove-mentioned and other disadvantages of the heretofore-known devicesand methods of this general type and which provide improved sealingelements and methods for the manufacture thereof.

With the foregoing and other objects in view there is provided, inaccordance with the invention, a sealing ring for a header of animplantable device, the sealing ring comprising:

an outer ring formed with, or consisting essentially of, ahigh-performance thermoplastic material being a polyaryl or aliquid-crystal polymer, with the polyaryl being selected from the groupconsisting of a poly(aryl ether sulfone), a polyaryletherketone, and apolyphenylene sulfide; and

an inner ring formed with, or consisting essentially of, a liquidsilicone or a polyurethane;

wherein said inner ring and said outer ring are arranged with a form fitrelative to one another.

In other words, the objects of the invention are achieved with a sealingring for use in a header of an implantable device is provided. Thesealing ring according to the invention comprises the followingcomponents: an outer ring or core comprising or essentially consistingof a high-performance thermoplastic material, and an inner ringcomprising or essentially consisting of a liquid silicone or apolyurethane. The inner ring and the outer ring are arranged with aform-fitting, or positive, engagement into one another.

In accordance with the invention it is particularly provided that thehigh-performance thermoplastic material is selected from the groupcomprising a polyaryl and a liquid-crystal polymer, wherein the polyarylis selected in particular from a poly(aryl ether sulfone), apolyaryletherketone and a polyphenylene sulfide.

The term “liquid-crystal polymer” is used in the context of the presentspecification in the sense known and familiar to a person skilled in theart. A “liquid-crystal polymer” in particular denotes an aromaticpolymer that has highly ordered or crystalline areas in the melt or insolution. Non-limiting examples include aromatic polyamides such asaramid (Kevlar) and aromatic polyesters such as a polycondensate formedfrom 4-hydroxybenzoic acid and 6-hydroxynaphthalene-2-carboxylic acid(Vectran).

The term polysulfone or poly(aryl ether sulfone) in the context of thepresent specification particularly refers to a thermoplastic materialwith an aryl-SO₂-aryl sub-unit. Non-limiting examples of polysulfonesand poly(aryl ether sulfone) include polysulfone (CAS No. 25135-51-7),poly(arylene sulfone), poly(bisphenyl sulfone) (CAS No. 25135-51-7),Victrex HTA (CAS No. 121763-41-5), polyether sulfone (CAS No.25608-63-3) and polyphenylene sulfone (CAS No. 25608-64-4).

In the context of the present specification, a thermoplastic materialwith an aryl-O-aryl-C(O)-aryl sub-unit, that is to say aryl groups whichare always linked to one another alternately via a keto group (—C(O)—and an ether group (—O—), is referred to as poly(aryl ether ketone). Anon-limiting example is polyether ether ketone (PEEK, CAS No.29658-26-2).

In the context of the present specification, a thermoplastic materialwith an aryl-S-aryl sub-unit, that is to say aryl groups which are eachlinked to one another via a sulfide group (—S—), is referred to as apolyphenyl sulfide. A non-limiting example is poly(thio-p-phenylene)(CAS No. 26125-40-6, 25212-74-2).

The above-mentioned polyaryls and the liquid-crystal polymeradvantageously enable an efficient attachment to resins, for exampleepoxy, which typically are used in headers of implantable medicaldevices.

In particular, a thermoplastic elastomer which not only comprisespoly(organo)siloxanes, but also cross-linkable groups such as vinylgroups and Si—H groups, which typically are added in anoble-metal-catalysed reaction, is referred to as liquid silicone orliquid-silicone rubber in the context of the present specification. Inaddition, the liquid silicone may comprise additives, such asreinforcing substances and/or fillers.

Preferably, the polyurethane is a thermoplastic or elastic (elastomer)polyurethane.

In some embodiments of the sealing ring according to the invention, theinner ring forms at least one groove, wherein the groove has a base andtwo opposite sides, which extend from the base, and the outer ringengages in the groove in a form-fit manner.

In some embodiments of the sealing ring according to the invention, theouter ring has at least one aperture, in particular a slot, and theinner ring has at least one bar, which extends from one side of thegroove to the other side of the groove, and the at least one bar passesthrough the at least one aperture.

In some embodiments of the sealing ring according to the invention, theouter ring has two or more apertures or slots, in particular 3 aperturesor slots, and the inner ring has two or more bars accordingly, inparticular 3 bars, wherein the two or more bars pass through one of thetwo or more apertures, respectively.

In some embodiments of the sealing ring according to the invention, theouter ring is injection molded.

In some further embodiments of the sealing ring according to theinvention, the inner ring is injection molded.

In some further embodiments of the sealing ring according to theinvention, the inner ring is injection molded around the outer ring. Ifthe outer ring has at least one aperture, the at least one bar of theinner ring is advantageously formed in this way and engages through theat least one aperture in the outer ring, and the outer ring and theinner ring are arranged to each other in a form-fit manner.

In some embodiments of the sealing ring according to the invention, theliquid silicone is selected from a two-component mixture of any Shorehardness, which is biocompatible. In accordance with one exemplaryembodiment, the components may be selected from the group SILASTIC®BioMedical Grade Liquid Silicone Rubbers (Dow Corning Corporation) orSilpuran 6600 (Wacker Chemie AG).

In accordance with a further feature of the invention, there is provideda contact socket for an implantable medical device, in particular for aconnection head of an implantable medical device. The contact socketcomprises at least one sealing ring of the invention as outlined, or oneof the previously described embodiments of the sealing ring of theinvention.

Particularly, an assembly of an implantable medical device that ensuresan electrical connection between a current-generating orcurrent-emitting component (generator component, battery) or acurrent-detecting component (diagnosis component) of an implantabledevice and an electrode lead is referred to as a connection head orheader in the context of the present specification.

In particular, the contact socket according to the invention comprises aplurality of electrical contacts, wherein a sealing ring according tothe invention is arranged between each two electrical contacts. Theplurality of electrical contacts and the sealing rings arrangedin-between form a cavity, in particular a cylindrical cavity, which isdesigned to receive a plug of an electrode lead. Furthermore, theelectrical contacts are designed to transfer or receive electricalcurrents or pulses to/from the plug of the electrode lead. Theelectrical contacts for this purpose are typically in contact with acurrent-generating or current-emitting component (generator component,battery) or a current-detecting component (diagnosis component).

The electrical contacts of the contact socket according to the inventionare preferably spring contacts. The contact socket may also comprise aplug receptacle or socket (connector block) with threaded pin at the endor at the start of the contact socket. Such plug receptacles or sockets,similarly to the spring contacts, may be electrically insulated andsealed by a sealing ring according to the invention.

The contact socket according to the invention is also preferably castinto a block of a thermosetting plastic, wherein a connection head isthus formed. The thermosetting plastic is preferably a transparentplastic, particularly an epoxy resin.

With the above and other objects in view there is also provided, inaccordance with the invention, an implantable medical device, whichcomprises at least one sealing ring as described in any of theembodiments or a contact socket as described in any of the embodiments.

The implantable medical device is in particular a cardiac pacemaker, acardioverter-defibrillator, or a neurostimulator, such as a spinal cordstimulator.

The implantable cardioverter-defibrillator (ICD) is in particular adevice that has a stimulation part (pulse generator) and a diagnosticspart (for identifying dangerous rhythm disturbances), wherein thestimulation/diagnostics part, usually implanted under the skin in thevicinity of the left pectoral muscle, is connected to the rightventricle via an electrode lead. The electrode lead is guided here intothe right heart chamber typically via the superior vena cava.

The spinal cord stimulator is in particular a device for the treatmentof chronic neuropathic pain, in which a pulse generator is connected viaan electrode lead to the part of the nervous system to be treated, forexample to the posterior column of the spinal cord.

The implantable medical device typically has a housing formed from aresistant, biocompatible material, preferably titanium or a titaniumalloy, wherein device components, which are necessary for the intendeduse of the device, for example control units, power sources, pulsegenerators or diagnosis units, are arranged in the housing.

With the above and other objects in view there is also provided, inaccordance with the invention, a method for producing a sealing ring, inparticular the sealing ring as described. The method comprises thefollowing steps:

providing an outer ring comprising or essentially consisting of ahigh-performance thermoplastic material,

providing an inner ring comprising or essentially consisting of aliquid-silicone or a polyurethane, and

arranging the outer ring and the inner ring to each other in a form-fitmanner.

In accordance with the invention, it is provided in particular that thehigh-performance thermoplastic material is selected from the groupcomprising a polyaryl and a liquid-crystal polymer, wherein the polyarylis selected in particular from a poly(aryl ether sulfone), a poly(arylether ketone) and a polyphenylene sulfide.

In some embodiments of the method according to the invention, the innerring forms at least one groove, wherein the groove has a base and twoopposite sides, which extend from the base, and the outer ring engagesin the groove in a form-fit manner.

In some embodiments of the method according to the invention, the outerring has at least one aperture, in particular a slot, and the inner ringhas at least one bar, which extends from one side of the groove to theother side of the groove, and the at least one bar passes through the atleast one aperture.

In some embodiments of the method according to the invention, the outerring is provided by an injection molding process, wherein in particularthe outer ring is polished or cleaned after the injection molding.

In some embodiments of the method according to the invention, the innerring is provided by an injection molding process.

In some embodiments of the method according to the invention, the innerring is injection molded around the outer ring and is arranged to theouter ring in a form-fit manner.

In some embodiments of the method according to the invention, the outerring is pre-treated prior to being arranged in a form-fit manner, inparticular prior to being overmolded by the inner ring, in particularwith use of a plasma or an adhesion promoter (primers).

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin sealing ring made of a high-performance thermoplastic material andliquid silicone, it is nevertheless not intended to be limited to thedetails shown, since various modifications and structural changes may bemade therein without departing from the spirit of the invention andwithin the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1A and FIG. 1B show perspective, schematic views of an embodimentof the sealing ring according to the invention;

FIG. 2 shows a schematic view of an embodiment of the production methodaccording to the invention; and

FIG. 3A and FIG. 3B are sectional views of an embodiment of the contactsocket according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures of the drawing in detail and first,particularly, to FIGS. 1A and 1B thereof, the present invention relatesin particular to a sealing element 100 made of a PSU component 10 and anovermolding 20 made of LSR (liquid silicone rubber). The PSU componentis designed here in particular as an outer ring 10, and the LSRovermolding is designed as an inner ring 20.

The PSU core 10 performs the following functions and has the followingadvantages:

-   -   distance between 2 electrical contacts    -   limit stop for the assembly process    -   attachment surface for resin for forming the header    -   mechanical fixing to the silicone (apertures)    -   attachment surface for silicone possibly for plasma processes or        primer

The LSR overmolding 20 performs the following functions and has thefollowing advantages:

-   -   electrical insulation between two electrical contacts (provided        by spherical end-face sealing surfaces of the inner ring, which        leads to a form-fit connection between the electrical contacts,        when the contact socket is clamped)    -   potential separation between electrode and cavity    -   seal against infiltration of resin during the resin casting        (realised by the defined limit stop surface and resultant        technical zero gap between the PSU rim and the housing of the        electrical contact).        These constitute three independent sealing functions.

FIG. 1A illustrates an embodiment of the sealing ring 100 according tothe invention which consists of an outer ring 10 made of PSU and aninner ring 20 made of a liquid silicone or liquid-silicone rubber. FIG.1B shows a detailed view of the outer ring 10 and of the inner ring 20.The outer ring 10 has slots 13 (apertures), which are used to grip orclaw the inner ring 20 made of LSR. The inner ring 20 in turn forms agroove 21, which comprises a base 22 and two opposite walls, whichextend from the base. The outer ring advantageously has 2 or 3 bars,which extend from a wall 23 of the groove 21 to the other wall 23 of thegroove 21. These bars 24 each pass through a corresponding slot in theouter ring 10 and thus ensure a form-fit connection between the innerring 20 and outer ring 10.

The outer ring 10 is used in particular as a limit stop for assembly ofthe electrical contacts 30. Due to the used PSU, a particularly goodattachment to the epoxy resin that is used during course of manufactureof the header is possible, and this thus contributes to the electricalinsulation above the PSU core. In addition, the outer ring serves as aguide for the wiring ribbons between the electrical contacts 30, forexample of an 8-pole module, an an electrical feedthrough to theinterior of the housing. This assists the process in which the wiringribbons are welded onto the electrical contact 30. By design, anpotential separation of the wiring ribbons is thus also realised.

FIG. 2 shows a flowchart that outlines the manufacture of the sealingring 100 according to the invention. The PSU core or outer ring 10 isfirstly provided by an injection molding process. As appropriate, theouter ring 10 is pre-treated by a vibratory finishing (barrel finishing)or by a cleaning process. The outer ring 10 is preferably additionallyplasma-treated or primed (treatment with an adhesion promoter) toprovide improved adhesion of the LSR 20. LSR is then injection-moldedaround the outer ring 10, wherein the LSR then forms the inner ring 20.If the outer ring 10 has slots 13, these are filled by the LSR, whereinan inner ring 20 with groove 21 and bars 24 is thus formed, wherein thebars 24 then pass through the corresponding slots 13, and a form-fitconnection is formed between outer ring 10 and inner ring 20.

FIG. 3A shows schematic sectional view of a contact socket 200 accordingto the invention, with FIG. 3B showing an enlarged partial view. Thecontact socket has a plurality of electrical contacts 30, in particularspring contacts, between each two of which a sealing ring 10 accordingto the invention is arranged. The contact socket 200 has a cavity in itsinterior, in particular a cylindrical cavity, which is designed toreceive a plug of an electrode lead. Here, the electrical contacts 30are used to conduct a current or electrical pulse between the plug ofthe electrode lead and the current-emitting or current-detectingcomponents of an implantable device (for example ICD), which areaccommodated in the housing of the device. The electrical contacts 30are connected to the interior of the housing in particular via wiringribbons.

In order to provide the liquid silicone, the components A and B, the 40Shore Material LSR Silastic 7-6840 (Dow Corning Corporation), were mixedwith one another in a ratio of 1:1 and were annealed or tempered toprovide an improved final cross-linking of the silicone material in acirculating air furnace (=post cure process). In principle, however,other Shore hardnesses of the LSR Silastic product family are alsosuitable, for example 30, 50 or 60. The temperature of the tempering isdependent in particular on the material of the core, in particular onits melting point or glass transition temperature. In the case of a PSUcore 10, tempering is performed at a temperature of approximately 150°C. for 12 hours. In the case of a PEEK core 10 higher temperatures maybe used. Alternatively, liquid silicones of the Silpuran 6600 productfamily with Shore hardnesses between 40 and 60 can also be used.

1. A sealing ring for a header of an implantable device, the sealingring comprising: an outer ring formed with, or consisting essentiallyof, a high-performance thermoplastic material being a polyaryl or aliquid-crystal polymer, with the polyaryl being selected from the groupconsisting of a poly(aryl ether sulfone), a polyaryletherketone, and apolyphenylene sulfide; and an inner ring formed with, or consistingessentially of, a liquid silicone or a polyurethane; wherein said innerring and said outer ring are arranged with a form fit relative to oneanother.
 2. The sealing ring according to claim 1, wherein said innerring is formed with at least one groove having a base and two oppositesides that extend from said base, and said outer ring engages in saidgroove with a form-fit engagement.
 3. The sealing ring according toclaim 2, wherein said outer ring is formed with at least one apertureand said inner ring has at least one bar, which extends from one side ofsaid groove to the other side of the groove, and said at least one barpasses through said at least one aperture.
 4. The sealing ring accordingto claim 3, wherein said at least one aperture formed in said outer ringis a slot.
 5. The sealing ring according to claim 1, wherein said liquidsilicone is selected from a two-component mixture of any Shore hardnesswhich is biocompatible.
 6. The sealing ring according to claim 1,wherein said outer ring is an injection-molded element.
 7. The sealingring according to claim 1, wherein said inner ring is injection-moldedaround said outer ring.
 8. A contact socket for an implantable medicaldevice, the contact socket comprising at least one sealing ringaccording to claim
 1. 9. An implantable device, comprising a sealingring according to claim 1 or a contact socket according to claim 8, andbeing an implantable cardioverter-defibrillator or an implantable spinalcord stimulator.
 10. A method for producing a sealing ring, the methodcomprising the following steps: providing an outer ring formed with, orconsisting essentially of, a high-performance thermoplastic materialselected from the group consisting of a polyaryl and a liquid-crystalpolymer, wherein the polyaryl is selected from the group consisting of apoly(aryl ether sulfone), a polyaryletherketone, and a polyphenylenesulfide; providing an inner ring formed with, or consisting essentiallyof, liquid-silicone or polyurethane; and arranging the outer ring andthe inner ring relative to one another with a form fitting engagement,to thereby form the sealing ring according to claim
 1. 11. The methodaccording to claim 10, which comprises forming the inner ring with atleast one groove, the groove having a base and two opposite sidesextending from the base, and placing the outer ring to engages in thegroove with a form fit.
 12. The method according to claim 11, whichcomprises forming the outer ring with at least one aperture andproviding the inner ring with at least one bar that extends from oneside of the groove to the other side of the groove, and passing the atleast one bar through the at least one aperture.
 13. The methodaccording to claim 12, wherein the at least one aperture formed in saidouter ring is a slot.
 14. The method according to claim 10, whichcomprises forming the outer ring with an injection molding process, andpolishing or cleaning the outer ring after the injection moldingprocess.
 15. The method according to claim 10, which comprises formingthe inner ring with an injection molding process.
 16. The methodaccording to claim 15, which comprises injection-molding the inner ringaround the outer ring and arranging the inner ring with a form-fit tothe outer ring.
 17. The method according to claim 10, which comprisespre-treating the outer ring prior to being arranged in the form-fitengagement with the inner ring.
 18. The method according to claim 17,which comprises pre-treating the outer ring prior to being overmolded bythe inner ring.
 19. The method according to claim 17, which comprisespre-treating the outer ring with use of a plasma or an adhesionpromoter.